Fill the gaps with an appropriate word to refer to the underlined parts of the sentences.

1. So you were talking about animal rights? That’s quite a big issue nowadays.
2. We are running out of funds. How do you propose we should deal with the ?
3. Is there life on other planets? This is a nobody has yet been able to answer.
4. (teacher to the class) You can write your essay on ‘My best holiday ever’. If you don’t like that , I’ll give you another one.
5. She thinks we should all fly around in tiny little helicopters. This to the traffic problem in cities is rather new and unusual. I wonder if it is viable?